The purpose of the proposed project is to employ a surface-initiated photopolymerization reaction for highly sensitive detection of hybridization to a DNA microarray. DNA microarrays have the potential for high impact in health-related applications, however, a number of challenges must be overcome. One of these, and the focus of this proposal, is the development of a rapid, inexpensive and reliable method to detect a small number of hybridization events (approximately 100) for use in robust, portable, user-friendly devices. The proposed photopolymerization detection scheme will be tested in the Flu Chip, a novel inexpensive device designed to diagnose and subtype the influenza virus rapidly. Photoinitiators will be attached to the surface of DNA microarrays only in places where hybridization between the viral DNA of interest and the probe DNA of the microarray has occurred. Fluorescent monomer will be placed in contact with these hybridized arrays, and in the presence of ultraviolet radiation, a fluorescent polymer will grow from the surfacebound initiators. Unreacted monomers can be easily rinsed from areas of the array where no hybridization occurred, and the remaining surface-immobilized fluorescent polymer reveals which areas of the microarray contain captured viral genetic material.